Brakes - At my wits end

[youngricharduk]

Hi

I had a Scott Scale 720 Carbon mountain bike that I sold to my uncle.

Before I got rid of it I had an issue with brake squeal, I tried multiple sets of pads and had the rotors re-skimmed.

I made sure never to contaminate the pads or discs but the squeal still remained. Every time i got rid of the squeal it would come back after a few rides. I used the bike for years without any issue prior to this.

When i sold the bike again I thought it was sorted but it became un-rideable again for my Uncle. The only thing left I thought it could be was the calipers were leaking ever so slightly and contaminating the pads, so I took the bike back ordered all new brakes and discs, then a few weeks ago I replaced the whole lot (new brakes, calipers, rotors, pads and hoses etc).

I took the bike out for a ride, broke the new pads in properly and finally the brakes were not squealing. FF to today and my uncle has said he's been out twice and the front brake is squealing like a cat again.

How can that be possible!!! (He hasn't cleaned the bike with anything since he got it back)

The brakes are Shimano Deore which I know arent the greatest but I normally find them reliable enough, at least for a few years anyway.

[Bacon Is Proof]

Is he simply not braking hard enough? Discs don't like to be feathered.

[oddball1313]

This is of no help but the Shimano Ultegra discs on my Canyon Endurace are exactly the same, although in fairness in dry conditions they are Ok but the slightest bit of moisture and the squeeling begins.

The Campagnolo discs on my BMC don't do this but that's a bloody expensive way to solve the problem.

[youngricharduk]

Bacon Is Proof said:

Is he simply not braking hard enough? Discs don't like to be feathered.

The harder you brake the worse it is. I live near a hill in a small village and I heard him going past the end of my street. I have other bikes such as my Trek remedy 8 with guide r sram brakes and they don't make a sound.

[Bathroom_Security]

Any way you can swap the pad compound or change the brand of disk/pad. Cost you 10-15 quid for a pair of pads to test them out, disks might be a bit more

I run metal shimano pads in deore m6000 calipers with disks from the original sram guide r setup I had and they barely make a sound, even in the wet they are pretty good unless I am braking hard down something steep.

[take-good-care-of-the-forest-dewey]

Have you tried...in this order

Checking rotor and calliper bolts are tight.

Re-aligning calliper?

Re-aligning pistons?

Replacing anti-rattle spring. Did you reuse?

Cleaning the pistons with degreaser and cleaning brake dust / crap out? Then applying a very small amount of brake fluid onto the exposed piston and thently pumping the brakes - not too much, you'll push them out.

Small blob of silicone grease on the piston face?

[frisbee]

One of my replacement calipers has started leaking after a year. Post mount road which are pretty much Deore.

Reading around it appears some actually leak straight out of the box!

[Jimbo.]

Everything clean, threadlocked/greased and torqued down properly? I had all kinds of trouble with the old Avid Juicy-era self-aligning system: every screw, spacer and washer had to be surgically clean before being torqued down (normally to the upper limit!).